Factual error: Throughout the movie, you see Carlito using a Beretta 92F semi-automatic pistol. The movie is set in 1975, that model pistol wasn't introduced until the mid 80s.
Factual error: In the scene where the mobsters are chasing Carlito, they chase him on to subway and are about to get him when some New York City Police Recruits also board the same subway. The mistake is that this cannot be possible because New York City had a hiring freeze from 1974-1980, and the movie takes place around 1975, thus there could not have been any recruits around that time.
Other mistake: The scene in which Carlito and Kleinfeld are disposing of a body off of Kleinfeld's yacht, it is obvious that the body walks across the top of the yacht, even though they are supposed to be carrying him. Also, when is the last time you seen a body do a summersault when thrown?
Deliberate mistake: At the end of the film when Pacino and the gangsters are shooting each other on the escalator, the escalator takes a long time to get to the bottom, way too long.
Continuity mistake: There's a scene where Al ducks into a bar from a very wet and rainy night outside, and he's soaking wet. However a couple of shots later his hair appears perfectly blowdried.
Visible crew/equipment: In the last sequence at the train station, when Carlito runs through the main hall after the shooting on the escalator, you can see whole crew standing next to the wheeled platform with camera operator on it.
Continuity mistake: In a scene at a coffee shop, the same few period vehicles keep passing by on the street in the background.
Revealing mistake: In the last scene of the movie after Carlito gets shot by Benny Blanco and Carlito's friend says "Let's get out of here", Benny Blanco turns and shoots him too. Right before he shoots him though, you can see Carlito's friend's eyes close and put on a facial expression as if bracing for the shot.
Plot hole: Carlito's cousin was killed in the beginning at the sleazy bar, but you can see him walking down the stairs before Carlito goes to the train platform. The background is blurred but you can tell it's him.